This invention is directed to the structure of an electric watch wherein a single battery contact spring is mounted at the rear of the watch to contact and restrain two watch batteries.
Electric watches often have two batteries therein and in digital watches with modern CMOS electronics, two batteries are necessary to provide reliable operating voltage. In prior watches two battery hatches have been provided in the watch back so that each of the batteries was individually accessible. Such a structure is shown in E. C. Ho, R. J. Belardi and K. H. Reissmueller U.S. Pat No. 3,846,971. It is also seen in R. F. Zurcher and I. B. Merles U.S. Pat. No. 3,838,568.
From these prior patents the complexity of the watch case can be seen. First of all, the watch back can be installed and secured onto the watch case in only one angular orientation so that the hatches are correctly positioned over the batteries. This requirement for positioning prevents employment of a turnable screw-on watch back. Furthermore, two hatch covers and two battery springs are required so that more parts are required and the thickness of the total watch is built up by the watch case structure.
It is necessary to resiliently urge the batteries into their wells so that they make contact with electronics at the upper contact of the batteries away from the watch back. It is also necessary to make electric contact with the lower contact of the battery to complete the series connection so that the series voltage addition of the two batteries is applied to appropriate electronics within the watch. In some cases, such as shown in the above-mentioned prior patents, the intermediate voltage is applied to the watch case and this can be the responsibility of the battery springs.